Truck bed tool box lid

ABSTRACT

A truck bed tool box lid formed with a top sheet member and a liner sheet member joined to define an interior cavity, where the interior cavity is filled with a self-curing, self-expanding foam material which bonds to the top sheet and the liner sheet upon expansion and curing to create a rigid composite structure.

[0001] This application claims the benefit of U.S. Provisional Application Ser. No. 60/181,858, filed Feb. 11, 2000.

BACKGROUND OF THE INVENTION

[0002] This invention relates generally to the field of truck bed tool boxes, an accessory which is essentially a storage cabinet designed for outdoor exposure that is mounted in the open bed of a pick-up truck, generally just to the rear of the passenger compartment. Such a tool box typically comprises a generally rectangular, open topped lower receptacle or tub, to which is pivotally attached one or more lid members. A single lid is typically attached by hinges affixed along the longitudinal rear edge of the lid and the back wall of the tub if a single lid, or a pair of lids are affixed by hinges affixed transversely adjacent the lateral middle of the tub. Closure means, latches, locks or the like are provided to secure the lid or lids in the closed positioned. The box may be provided with lift cylinders and detent means to maintain the lid in the open position, or other features. Such devices are well known, and are typically of constructed of relatively rigid, aluminum sheet material, typically in thicknesses of from 0.080 to 0.063 mil, with the individual panels welded or mechanically fastened to define the box structure. Typical truck bed tool box sizes range from 54 to 75 inches in width, from 19 to 28 inches in depth and from 13 to 14 inches in height.

[0003] Because the lid is main movable component of the tool box, it is subjected to repetitive forces from many directions and is therefore the component most susceptible to damage or failure. It is necessary to impart significant rigidity to prevent the lid from bending, crimping, torqueing, twisting, failing or becoming misaligned relative to the tub. If the lid becomes twisted or otherwise misaligned, proper closure to seal the box from the elements becomes difficult or impossible, and the tool box must then be repaired or replaced. It is standard practice to fasten structural bracing members on the underside of the lid to increase planar rigidity, the bracing members extending either longitudinally or laterally, but the efficacy of these brace members is limited by the desire to minimize cost and weight factors, such that manufacturers attempt to use the smallest or the fewest brace members which will still provide a minimally acceptable increase in rigidity and structural integrity. Another method for increasing the rigidity and structural integrity of the lid is to provide an interior liner sheet to form a cavity into which pre-cured, cut-to-size, rigid foam sheets are inserted. While this improves the desired characteristics, there is significant waste and cutting the foam sheets to size results in environmental hazards.

[0004] It is an object of this invention to provide an improved lid for a truck bed tool box, where the lid has increased resistance to detrimental forces such that it has greater rigidity and resistence to bending and torqueing than standard constructions, where the improved lid is relatively easy to manufacture with reasonable costs. These and other objects are accomplished by providing a lid with an inner liner which defines an interior cavity to receive a self-curing, self-expanding injected foam, whereby the foam expands after injection into the interior cavity to create a high-density structural panel with the cured foam bonded and adhered to the lid components.

SUMMARY OF THE INVENTION

[0005] The invention is an improved lid for a truck bed tool box, and the method of manufacturing the improved lid, where the lid comprises an outer layer of aluminum or similar sheet material, the outer layer comprising a generally rectangular top sheet member, a longitudinal front edge member, two lateral edge members and a longitudinal rear edge member, where the edge members depend from the top sheet member and overlap the upper edges of the truck box rectangular tub or base. A liner sheet member of aluminum or similar material is positioned to the inside of the top sheet member in a generally parallel manner and spaced a short distance from the top sheet member to create an internal cavity, where the liner sheet member is connected to either the inside of the top sheet member or to the edge members, or to both, by suitable fastening means, such as by welding, thus defining an interior cavity. One or more injection ports are provided, preferably in the liner sheet member, whereby a self-expanding and self-curing, relatively high-density, foam is injected to completely fill the interior cavity. The cured, expanded foam adheres to the inside surfaces of the top sheet member and the inside surface of the liner sheet member, creating a rigid composite structure whereby bending and torqueing forces are more evenly distributed through the composite structure, such that the lid is able to withstand much greater detrimental forces without permanent flexing, bending, crimping or failure.

BRIEF DESCRIPTION OF THE DRAWINGS

[0006]FIG. 1 is a perspective view showing a truck tool box with the lid of the invention in the closed position attached to the tub.

[0007]FIG. 2 is a bottom view of the lid.

[0008]FIG. 3 is a cross-sectional view of the lid.

[0009]FIG. 4 is a partial cross-sectional view of an alternative embodiment of the lid.

[0010]FIG. 5 is a partial cross-sectional view of another alternative embodiment of the lid.

[0011]FIG. 6 is a partial cross-sectional view of another alternative embodiment of the lid.

DETAILED DESCRIPTION OF THE INVENTION

[0012] With reference to the drawings, the invention will now be described in detail with regard for the best mode and the preferred embodiment.

[0013] As shown in FIGS. 1 through 3, the invention in general comprises an improved lid 20 for use on a truck bed tool box 10 of the type configured to be positioned in the bed of the open cargo area of a pick-up truck, usually abutting the rear of the cab and extending laterally across the bed. The box 10 typically comprises a generally rectangular tub or base member 15 having upstanding side walls 11 with upper edges 12. The box 10 is provided with latching or locking means 13 to secure the lid 20 in the closed position, and the lid 20 is pivotally joined to the tub 15 by hinge means 14. The major structural components are preferably composed of sheet metal, such as aluminum. In the embodiment illustrated, the box 10 is shown as comprising a single lid 20, but it is to be understood that the structure as described herein is applicable to truck bed tool boxes having pairs of lid members, in which case the lid members are pivotally joined to the tub along a lateral edge, preferably an interior lateral edge with the hinges mounted transversely.

[0014] The lid 20 comprises a generally planar top or outer sheet member 21 from which depend a longitudinal front edge member 22, a pair of opposing lateral edge members 23 and a rear edge member 24, where the hinge means 14 is connected in some manner to the rear edge member 24 such that the lid 20 can be pivoted preferably at least 90 degrees from the tub 15 in the open position. Lift cylinders or detent means, not shown but known in the art, may be provided to retain the lid 20 in the open position. The edge members 22, 23 and 24 form a complete perimeter around the top sheet member 21, which is sized to allow the edge members 22, 23 and 24 to overlap the upper edges 12 of the tub walls 11 to preclude entry of rain, dirt and other detrimental environmental effects. All or some of edge members 22, 23 and 24 may be provided with a hem 25, which is formed by bending the outer portion of the edge member 22, 23 or 24 back upon itself such that a rounded configuration is presented in areas where the user may contact the edge members 22, 23 and 24.

[0015] The lid 20 further comprises a liner sheet member 30, preferably formed of a sheet metal such as aluminum, which is mounted on the inside of the top sheet member 21. The liner sheet member 30 is preferably planar and substantially coextensive and parallel with the top sheet member 21 in the horizontal direction, but is separated from the top sheet member 21 a short distance to define an interior cavity 42. The liner sheet member 30 is connected to either the top sheet member 21 or edge members 22, 23 and 24. As shown in FIG. 2, the edges 31 of the liner sheet member 30 may be connected to the edge members 22, 23 and 24 by stitch welds 99, and the liner edges 31 may also be hemmed. Preferably the stitch welds 99 extend for short distances of one inch or less, as this technique minimizes damage to the aluminum sheets from the heat of welding. Other methods for affixing the liner sheet member 30 to the top sheet member 21, such as mechanical fasteners or the like may also be utilized.

[0016] Preferably, an internal sealing member 34 is disposed along the outer perimeter of the interior cavity 42, generally adjacent the perimeter of the line sheet member 30 and near the edge members 22, 23 and 24. The internal sealing member 34 extends from the top sheet member 21 to the liner sheet member 30. The internal sealing member 34 may be comprised of any suitable material which impedes or blocks the flow and expansion of the injected foam 40, and preferably comprises an open or closed cell foam strip generally rectangular in cross-section, which is affixed to the interior of the top sheet member 21 or the liner sheet member 30 by adhesives or other suitable means prior to assembly of the top sheet member 21 and liner sheet member 30. Internal sealing member 34 retains the foam 40 within a defined area and prevents the foam 40 from expanding through the junction of the top sheet member 21 and the liner sheet member 30 between the stitch welds 99.

[0017] Alternatively, the liner sheet member 30 may be formed with shoulder members 32 and connected to the inside of the top sheet member 21 by stitch welds 99, as shown in FIG. 4. In another embodiment, shown in FIG. 5, the liner sheet member 30 is formed with shoulder members 32 and depending flange members 33, where the flange members 33 are positioned within the hems 25 of the edge members 22, 23 and 24. Furthermore, as shown in FIG. 6, the liner sheet member 30 may be formed with depending flange members 33, which are positioned with the hems 25 of the edge members 22, 23 and 24.

[0018] The liner sheet member 30 is provide with one or more injection ports or apertures 41, which allow a self-expanding, self-curing foam material 40 to be injected into the interior cavity 42, where it self-bonds and adheres to the inside of the top sheet member 21 without need for application of a separate adhesive material, the liner sheet member 30 and the edge members 22, 23 and 24, depending on the configuration of the liner sheet member 30, to create a rigid, integral, composite material lid 20 which has improved damage- and failure-resistance properties. A suitable foam 40 for injection into the interior cavity 42 is a combination of ISOFOAM R1322B, a polyurethane polyol blend containing a surfactant, catalyst, flame retardant and hydrochlorofluorocarbon, and ISOFOAM I-0732A, a polyurethane isocyanate, sold by IPI International, Inc., which upon reaction forms a foam of relatively high density which adheres to the aluminum members and cures into a rigid body.

[0019] It has been found that the presence of the cured foam 40 in the interior cavity 42 bonding the upper sheet member 21 to the liner sheet member 30 is a much stronger construction than that of the previously known constructions, enabling thinner metal sheets to be utilized in the construction of the lids 20 and obviating the need for interior bracing members, which lowers material costs yet still provides improved properties over standard constructions. For example, a suitable lid 20 is formed with a one half to three quarter inches in depth cavity 42 between a liner sheet member 30 of only 0.050 mil thickness and a top sheet member 21 of only 0.063 mil thickness.

[0020] Preferably, the tub 15 is produced by cutting and folding an aluminum sheet to create the front, bottom and back walls with the side walls welded to create the full base structure. The lid 20 is preferably formed by cutting and folding a single aluminum sheet to form the top sheet member 21, front edge member 22, lateral edge members 23 and rear edge member 24. The interior sealing member 34 is affixed to the interior of the top sheet member 21 or to the interior of the liner sheet member 30, and the liner sheet member 30 is then welded in place to the top sheet member 21. The lid 20 is then placed into a clam-style jig with the liner sheet member 30 temporarily braced such that it does not flex outward after the foam 40 begins to expand. The foam is injected in metered amount under controlled conditions such that the interior cavity 42 is filled to capacity upon expansion and curing. The injection ports 41 are covered by one or more adhesive members so that the foam 40 does not expand through the injection ports 41. The lid 20 is left in the jig for sufficient time such that the vast majority of the expansion has occurred, and the lid 20 is then removed from the jig and allowed to fully cure. With this structure, the lid 20 can be further processed, such as by powder coating, painting or the like to produce aesthetic improvements, some of which processes require high temperature environments detrimental to the foam 40, with the foam 40 later injected into the interior cavity 42 to increase structural rigidity and stiffness.

[0021] Tests on lids 20 constructed as described versus standard lids or lids with inserted pre-cured, cut-to-size, foam panels show remarkable improvements relative to desired stiffness characteristics. In a first test apparatus, lids were clamped or secured along one end to a horizontal platform such that approximately half the lid extended beyond the edge of the platform. Pressure was applied using a hydraulic jack to the free end of the lid adjacent the free lateral edge member 23 at the midpoint or center. Pressure was applied until the lid failed, with failure defined to be crimped edges with the lid taking on a permanently deformed set. The lid 20 of the invention was able to withstand up to 480 psi of vertical pressure prior to failure, while the standard lid construction failed at 250 psi and the insert construction failed at 360 psi. In addition, the standard lid construction failed at only 1.25 inches of deflection, the insert construction failed at only 4 inches of deflection, while the lid 20 of the invention did not fail until deflected 6.25 inches. In other words, the lid 20 of the invention could be flexed slightly less than 6.25 inches at 480 psi and would resume its pre-test shape without any permanent deformation.

[0022] In a second test, the pressure was applied to one corner of the free end of the lids to introduce torque. For the torque load tests, the invention withstood up to 490 psi without failure, while the standard lid failed at 280 psi and the insert lid failed at 310 psi. The standard lid failed at only 1.25 inches of deflection and the insert construction failed at only 5 inches of deflection. The lid 20 of the invention did not fail even at deflection of almost 7.5 inches under the failure definition set forth above.

[0023] It is contemplated that equivalents and substitutions to certain elements set forth above may be obvious to those skilled in the art, and thus the true scope and definition of the invention is to be as set forth in the following claims. 

We claim:
 1. A lid for a truck bed tool box, the lid comprising: a top sheet member having a depending front edge member, a depending rear edge member and depending lateral edge members; a liner sheet member joined to said top sheet member so as to define an internal cavity; and a rigid, expanded, cured foam disposed within said internal cavity and bonded to said top sheet member and said liner sheet member, characterized in that said foam is injected into said cavity in an uncured, unexpanded state and expands and cures so as to self-bond to said top sheet member and said liner sheet member to form an integral, composite lid.
 2. The lid of claim 1 , further comprising an internal sealing member disposed within said internal cavity and disposed between said top sheet member and said liner sheet member, whereby said sealing member retains said foam.
 3. The lid of claim 1 , wherein said liner sheet member is welded to said top sheet member.
 4. The lid of claim 1 , wherein said foam is a polyurethane.
 5. The lid of claim 1 , characterized in that said lid remains uncrimped with no permanent set upon deflection up to approximately 6.25 inches under up to approximately 480 psi when said lid is secured on a horizontal platform with approximately half said lid extending beyond said platform and subjected to center pressure adjacent one of said lateral edge members.
 6. The lid of claim 1 , characterized in that said lid remains uncrimped with no permanent set upon deflection up to approximately 7.5 inches under up to approximately 490 psi when said lid is secured on a horizontal platform with approximately half said lid extending beyond said platform and subjected to corner pressure adjacent one of said lateral edge members.
 7. The lid of claim 1 , wherein said top sheet member is formed of aluminum material having a thickness of approximately 0.063 mil.
 8. The lid of claim 1 , wherein said liner sheet member is disposed generally parallel to said top sheet member.
 9. The lid of claim 1 , wherein at least one of said front edge member, said depending rear edge member and said depending lateral edge members is provided with a hem.
 10. The lid of claim 1 , wherein said internal cavity is approximately one half to three quarter inches in depth.
 11. A lid for a truck bed tool box, said lid produced by the steps of: providing a top sheet member having a depending front edge member, a depending rear edge member and depending lateral edge members; providing a liner sheet member; joining said liner sheet member to said top sheet member so as to define an internal cavity; injecting a self-expanding, self-curing foam into said internal cavity in an amount such that said internal cavity is completely filled upon expansion of said foam; allowing said foam to expand and cure, such that said foam is adhered to said top sheet member and said liner sheet member and such that said top sheet member, said foam and said liner sheet member form a rigid composite member.
 12. The lid of claim 11 , wherein said joining step is performed by welding.
 13. The lid of claim 11 , wherein said joining step is performed by disposing said liner sheet generally parallel to said top sheet member.
 14. The lid of claim 11 , further comprising the steps of providing an internal sealing member and disposing said internal sealing member between said liner sheet member and said top sheet member prior to said joining step.
 15. The lid of claim 11 , wherein said top sheet member is produced by cutting, folding and welding a single sheet of aluminum. 